If `sigma` is the surface charge density off a charge for a charged sphere of radius R. kept in a medium of dielectric constant K, then the electric intensity at a distance r from its centre where rgtR, is (`epsi_(0)`=permittivity of free space)

Options

A. `(sigmar)/(epsi_(0)KR)`
B. `(sigmaR^(2))/(epsi_(0)Kr^(2))`
C. `(sigmaR)/(epsi_(0)Kr)`
D. `(sigmar^(2))/(epsi_(0)KR^(2))`

Answer

B

Explanation

Intensity `E=(1)/(4piepsi_(0))(q)/(Kr^(2))`
But the charge on the sphere `=4piR^(2)sigma=q`
`thereforeE+(1)/(4piepsi_(0))xx(4piR^(2)sigma)/(Kr^(2))=(R^(2)sigma)/(epsi_(0)Kr^(2))`